The primary aim is toward an understanding of the mechanisms of bisensory interactions, with stress placed on binaural hearing and on detection under conditions of shared attention. In the case of binaural interaction, we will concentrate on two factors. One concerns the sensitivity of the binaural nervous system as discrete from that of the monaural. Here we will plot the audiogram of binaural interaction by presenting dichotic tones to an observer, and then increasing the interaural difference of intensity, delta I, until he can no longer discriminate it from one that is monaural. Our recent work on the limitations of high stimulus rates on binaural temporal interaction (detections of interaural differences of time delta t) has produced a model for the ways in which the nervous system deals with high frequencies. We will pursue this model through analysis of neural firing patterns recorded in response to trains of clicks whose Interclick Interval can be varied. Finally, we will continue our present work on the mechanisms of shared attention. We will test our two-factor model of attention by forcing observers to attend to a task for which the attentional needs are predictable (in this case a visual tracking game) while testing for residual attention by sampling a periodically on a different sensory channel (in this case, detections of tones in noise). Similarly, the model will be applied to situations where the channels are defined as different auditory frequencies or directions.